APOLLO 17 STATION 3 SAMPLES: WHAT TO EXPECT AMONG LITHOLOGIC COMPONENTS IN ANGSA DOUBLE DRIVE TUBE 73001 AND 73002. B. L. Jolliff1, K. Wang1, R. L. Korotev1, S. B. Simon2, J. J. Papike2, C. K. Shearer2 and the ANGSA Science Team3. 1Department of Earth & Planetary Sciences and the McDon-nell Center for Space Science, Washington University in St. Louis, MO 63130; 2Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131; 3https://www.lpi.usra.edu/ANGSA/teams/ (bjolliff@wustl.edu).

Introduction: With the opening of the previously un-studied Apollo 17 double drive tube 73001/73002 as part of the Apollo Next Generation Sample Analysis (ANGSA) program [1-3], we present in this abstract in-formation about the lithologic makeup of rock compo-nents of Station 3 regolith. Specifically, we report com-positions and lithic component proportions of the 2-4 mm rock fragments (73243) of Station 3 trench soil 73240 (see also [4]). The trench was dug on the ejecta blanket and ~40 m from the rim of 620 m diameter Lara crater, and just beyond the rim of an ~10 m crater infor-mally named Ballet (Fig. 1) [5-7]. Double drive tube 73001/2 was collected ~10 m southeast of the trench and ~50 m from the rim of Lara crater. Station 3 was selected in part for its location on the “light mantle” and contains landslide material from South Massif [7,8]. As such, soil samples from Station 3, including 73001/2, which sam-pled to a depth of ~70 cm, offer the possibility to identify lithologic components specifically associated with the landslide and perhaps ejecta from Tycho crater, which may have triggered the landslide [8,9].

Station 3 soils: The station 3 soils include 73210 and

trench samples 73220, 73240, 73260, and 73280 (Fig. 2). Comparing data from [10 Wänke et al., 11 Rhodes et al., 1974, and 12 K&K92], the compositions of these soils are very similar despite significant variations in color and apparent reflectance in photographs of the trench soils. Judging by IS/FeO values, ranging from 18 to 45, these soils are generally submature. Of measured

soil parameters, only the agglutinate content and ma-turity vary significantly and they correlate approxi-mately with the color variations; 73240 is least mature and bright whereas 73260 is most mature and dark (Fig. 2). In a study of Apollo 17 compositional components, Korotev and Kremser [12] determined that for average Station 3 soil, impact-melt breccia and “anorthositic norite” components dominate the soil composition (91 wt.%) with mare basalt and orange glass accounting for only 8.5%.

Station 3 Rock particles in soils: A study of the 2-4 mm rock fragments in the upper 5 cm of the trench se-quence (73243) using Instrumental Neutron Activation Analysis (INAA) [4], summarized in Table 1 and Fig. 3, showed that mafic impact-melt breccias (IMB) are most abundant (36 wt.%), followed by regolith breccias and agglutinates (21%) and feldspathic lithologies (~20%). Mare basalt fragments compose ~12%. Only four of 109 rock fragments have FeO contents low enough to qualify as anorthosite mineral assemblages (>90% plagioclase).

Table 1. Lithic components (rock fragments) in 73243 Rock Classification By mass: No. Rocklets Impact Melt Breccia 36.2 43 Regolith Bx & Agglutinates 20.9 25 Feldspathic Lithologies 19.1 18 Alkali Lithologies 4.8 3 Other/Fragmental Breccia 6.8 8 Mare Basalt 11.6 11 Meteoritic contaminated 0.6 1 Sum 100.0 109

Figure 2. Station 3 trench, 10-15 cm deep. Gnomon legs are 50 cm apart. Portion of AS17-138-21148. After [ref: Meyer, 2010, Lunar Sample Compendium]

Figure 1. Planimetric map of Station 3 [5]; DT: drive tube.

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Others fragments correspond to the compositional com-ponent referred to by [12] as “anorthositic norite” and these include relatively feldspathic, polymict breccias such as those indicated below as “Feldspathic” (Fig. 3)

Bence et al. [13] also studied 2-4 mm rock fragments in Apollo 17 soils, including 26 particles from trench soil 73263. They found that “dark matrix breccias” and crystalline-matrix IMBs are the most abundant (sum-ming to ~77%), feldspathic igneous lithologies (ANT) contribute 14%, and basalt, 8%. The “dark matrix brec-cias likely include fine-grained glassy-matrix regolith breccias as well as aphanitic melt breccias. These pro-portions are broadly consistent, to the extent they can be compared, with our chemical classification for rocklets in 73243; however, the trace-element chemistry pro-vides important clues to rock types and relationships that can be obscured by petrographic variations in breccias.

Station 3 Rocks: Known nonmare rock types at Apollo 17 include “noritic” impact-melt breccias of sev-eral compositional and petrographic types (poikilitic, aphanitic, incompatible-trace-element (ITE) - rich) [4, 14], feldspathic granulitic breccias, and Mg-suite igne-ous rocks including dunite, troctolite, troctolitic anor-thosite, norite, and anorthositic gabbro, and various reg-olith and fragmental breccias. Rocks collected at Station 3 include 73215 and 73235 aphanitic IMBs, 73216 and 73218 crystalline matrix IMBs, 73275 poikilitic IMB, 73217 unusual IMB, and 73255 IMB “agglomeritic bomb” [15]. These groups of impact-melt breccias have different clast contents as well as some distinctive pet-rographic and compositional characteristics. The “poi-kilitic” IMBs, more abundant in North Massif samples, are those most commonly taken to represent Serenitatis impact melt whereas the aphanitic and unusual IMBs among the station 3 rocks may come from Serenitatis or from another basin impact, e.g., Imbrium [14,16]; age-dating results are complex and inconclusive [17].

Tycho components? If ejecta from Tycho indeed struck the top of South Massif to cause the landslide about 110 million years ago [18 Drozd et al., 77], then a glass component in the soil might be the best means for

identifying such materials, similar to the iden-tification of ejecta from Copernicus in Apollo 12 soils, where ropy glasses of composition unlike typical Apollo 12 materials were found [19 Eberhardt et al.]. Vaniman et al. [20] sug-gested that perhaps KREEP-rich glasses found in the Apollo 17 (7000x) deep drill core could be Tycho ejecta; however, we now know from remote sensing that Tycho occurs in a KREEP-poor region of the Moon, calling into question whether a KREEP-rich signature is a good in-dicator of a Tycho origin. Also, such a com-ponent would have to record the ~110 Myr age associated with cosmic ray exposure evidence at the Apollo 17 site.

Given what is known today about Apollo 17 compositional and lithologic components, the Station 3 drive tube 73001/2 and other Station 3 samples collected in the light mantle may provide the best opportunity for a fresh search

for Tycho components as well as a new test of the hy-pothesis that Tycho ejecta caused the landslide. Of par-ticular interest will be lithic fragments in 73001/2 which represent regolith samples of distinct depths relative to samples from the trench (Fig. 2).

Acknowledgements: We thank NASA for support of the ANGSA Program via 80NSSC19K0958 to CKS.

References: [1] Shearer C. et al. (2020) this Conf. [2] Schmitt H. et al. (2020) This Conf. [3] Simon S. et al. (2020) this Conf. [4] Jolliff B. et al. (1996) Meteorit. Planet. Sci. 31, 116-145. [5] Parker R. et al. (1973) Apollo 17: Preliminary Science Report. SP-330 (1973) Apollo 17: Preliminary Science Report, NASA. [6] Schmitt H. (1973) Science 182, 681-690. [7] Wolfe E. et al. (1980) USGS Prof. Paper 1080. [8] Petro N. et al. (2020) This Conf. [9] Lucchitta B. (1977) Icarus 30, 80-96. [10] Wänke H. et al. (1974) Proc. Lunar Sci. Conf. 5th, 1307-1335. [11] Rhodes J. et al. (1974) Proc. Lunar Sci. Conf. 5th, 1097-1117. [12] Korotev R. and Kremser D. (1992) Proc. Lunar Planet. Sci. 22, 275-301. [13] Bence A. et al. (1974) Proc. Lunar Sci. Conf. 5th, 785-827. [14] Spudis P. and Ryder G. (1981) Proc. Lunar Planet. Sci. Conf. 12A, 133-148. [15] Ryder G. (1993) Catalog of Apollo 17 Rocks, Vol. 1-Stations 2 and 3 (South Massif). NASA JSC Pub. #26088, Houston, TX. [16] Ryder G. and Spudis, P. (1987) Proc. Lunar Planet. Sci. Conf. 17th in J. Geophys. Res. 92, E432-E446. [17] Mercer et al. (2019) Lunar Planet Sci. 50, #3049. [18] Drozd R. et al. (1977) Proc. Lunar Sci. Conf. 8th, 3027-3043. [19] Eberhardt P.et al. (1973) The Moon 8, 104-114. [20] Vaniman D. et al. (1979) Proc. Lunar Planet. Sci. Conf. 10th, 1185-1227.

Figure 3. Compositions of 109 rock fragments from sample 73243 (2-4 mm rock fragments from 73240) and lithologic classification on basis of composition. IMBs separated into two groups based on ITE contents.

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